1. Field of the Invention
The present invention relates to an LED (Light Emitting Diode) illumination unit, an LED illumination device, and an LED illumination system, including a plurality of LED chips and used for, for example, indoor ground illumination or wall surface illumination.
2. Description of the Related Art
FIG. 28 is a sectional view of an example of a conventional LED illumination device (for example, referring to Patent Document 1). An LED illumination device 90 shown in the figure includes a rectangular substrate 91, a plurality of LED chips 92 mounted on the substrate 91, a tube 93 accommodating the substrate 91, terminals 94, and a circuit 95 for turning the LED chips 92 on. A wiring, not shown in the drawings, connected to the LED chips 92 and the terminals 94 is formed on the substrate 91. The LED illumination device 90 is constructed such that the LED chips 92 can be enabled to emit light by plugging the terminals 94 into insert openings of a socket of general fluorescent lamp illumination equipment. As the LED chips 92 require low power consumption and have a long service life, improvements can be realized in aspects of cost and environment if the LED illumination device 90 is used to replace the fluorescent lamp. In addition, the fluorescent lamp illumination equipment for general use is illumination equipment mainly widely used for indoor general illumination, and for example, in Japan, refers to straight tubular fluorescent lamps specified in JIS (Japanese Industrial Standards) C7617 or annular fluorescent lamps specified in JIS C7618 using a 100 V power supply.
However, the conventional fluorescent lamp illumination equipment is constructed on the premise of presence of the terminals 94 at two ends and light emission in all directions. Therefore, if a plurality of LED illumination devices 90 is mounted on illumination equipment having a plurality of fluorescent lamps configured in series, non-illumination dark portions can be formed between neighboring LED illumination devices 90. Sometimes, the visual effect is poor. Or, when it is intended to illuminate a part of the wall surface, other parts than the part intended to be illuminated can also be illuminated if the LED illumination device 90 is used. As a result, for example, a light shield for covering half of the LED illumination device 90 needs to be disposed.    Patent Document 1: Japanese Laid-open Patent Publication No. H6-54103